Turbocharger Overhaul by Operators
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GIVEN that the maker's instructions 1--.1 are closely followed, it is now accepted that a typical operator of a turbocharged engine is qualified to dismantle the turbocharger, to fit new bearings and so on and to reassemble the unit in his workshop. Although balancing the rotor assembly should be performed by the manufacturer, rebalancing during overhaul is not normally necessary.
This advice was given by Mr. R. Tyner, Simms Motor Units, Ltd., turbocharger department, when he read a paper, " Turbocharging High Speed Diesel Engines " at a meeting of the Institute of Road Transport Engineers, Midland Centre, in Birmingham on Tuesday. Mr. Tytler emphasized that recent improvements in design had enabled operator maintenance" to be generally approved, despite the fact that the rotor had to be balanced with extreme accuracy.
On average, said Mr. Tytler, a turbocharger operated for about 3,000 hours or approximately 100,000 miles before an overhaul was required. Examples were known of a turbocharger running 5,000 hours without overhaul.
Commenting on the value of an inter
cooler, Mr. Tyner pointed out that the air-to-air type was the obvious choice for automotive applications. A vehicle engine was, however, running in this country equipped with an air-water heat exchanger for which the engine jacket water was used and in America the Caterpillar Company had developed a road vehicle engine fitted with a similar type of intercooler. In this case turhocharging gave a 50 per cent. increase in output and raised the b.m.c,p. to 151 p.s.i.
According to American opinion, the use of a turbocharger reduced the life of the engine between overhauls on a time basis, but the b.h.p./hour figure was increased. Accurately observed tests in this country had shown that an improvement in fuel consumption of at least five per cent. was normally provided by turbocharging,
Citing the case of ,a naturally aspirated 200 b.h.p. engine, Mr. Tytler estimated that the unit would weigh 12 lb. per b.h.p, and • would cost £5 per b.h.p. Equipping the engine with a turbocharger would raise its output to 270 b.h.p. and the cost per b.h.p. of the engine would be reduced to £4. The turbocharger would cost £70 to £80.